linux-kernel - Re: [PATCH v3 3/9] KVM: nSVM: reset nested_run_pending upon nested_svm_vmrun

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Message-ID: <262fc5f8-935d-dce2-314e-ce5db6e73940@redhat.com>
Date:   Thu, 9 Jul 2020 19:48:37 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/9] KVM: nSVM: reset nested_run_pending upon
 nested_svm_vmrun_msrpm() failure

On 09/07/20 16:53, Vitaly Kuznetsov wrote:
> WARN_ON_ONCE(svm->nested.nested_run_pending) in nested_svm_vmexit()
> will fire if nested_run_pending remains '1' but it doesn't really
> need to, we are already failing and not going to run nested guest.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
>  arch/x86/kvm/svm/nested.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index e424bce13e6c..1cc8592b1820 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -468,6 +468,8 @@ int nested_svm_vmrun(struct vcpu_svm *svm)
>  	enter_svm_guest_mode(svm, vmcb_gpa, nested_vmcb);
>  
>  	if (!nested_svm_vmrun_msrpm(svm)) {
> +		svm->nested.nested_run_pending = 0;
> +
>  		svm->vmcb->control.exit_code    = SVM_EXIT_ERR;
>  		svm->vmcb->control.exit_code_hi = 0;
>  		svm->vmcb->control.exit_info_1  = 0;
> 

I wouldn't complain if you added a kvm-unit-tests testcase for this...

Paolo